[coreboot-gerrit] Change in coreboot[master]: soc/intel/tigerlake: Disable C1 C-state Demotion

[Tim Wawrzynczak (Code Review)]

Tim Wawrzynczak has submitted this change. ( https://review.coreboot.org/c/coreboot/+/46438 )

Change subject: soc/intel/tigerlake: Disable C1 C-state Demotion
......................................................................

soc/intel/tigerlake: Disable C1 C-state Demotion

Disable C1 C-state auto demotion to decrease SoC power usage.

When set, processor will conditionally demote C3/C6/C7 requests
to C1 based on uncore auto-demote information.

BUG=b:161215906
TEST=Measure and confirm SoC power usage reduction for key use cases
 eg 'Google Meets video call'

Measured on instrumented boards for Volteer EVT and Delbin.

Below measurements for Volteer:

Google meets with 720p 	w/ auto-demotion   w/o auto-demotion
System Power 	        13.14W	              9.4W
SOC Power 	         7.9W	              5.4W

Signed-off-by: Ravi Sarawadi 
Signed-off-by: Shweta Malik 
Change-Id: I649cafbaf03917d76521aa5f76ec58d218e1a1b1
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46438
Tested-by: build bot (Jenkins) 
Reviewed-by: Tim Wawrzynczak 
---
M src/soc/intel/tigerlake/fsp_params.c
1 file changed, 4 insertions(+), 0 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Tim Wawrzynczak: Looks good to me, approved

diff --git a/src/soc/intel/tigerlake/fsp_params.c b/src/soc/intel/tigerlake/fsp_params.c
index 887241b..3427a61 100644
--- a/src/soc/intel/tigerlake/fsp_params.c
+++ b/src/soc/intel/tigerlake/fsp_params.c
@@ -365,6 +365,10 @@

/* EnableMultiPhaseSiliconInit for running MultiPhaseSiInit */
    params->EnableMultiPhaseSiliconInit = 1;
+
+	/* Disable C1 C-state Demotion */
+	params->C1StateAutoDemotion = 0;
+
    mainboard_silicon_init_params(params);
 }